This invention relates to a synergistic composition of plant growth nutrients and regulators. More specifically this invention relates to a novel combination of plant nutrients and regulators which are, in themselves, known to be beneficial to plant growth and regulation but which, in combination, show a significantly greater effect than when used separately, i.e. a synergistic effect.
It is known that metal proteinates, which are chelates of bio-essential metals with protein hydrolysate ligands, increase metal assimilation in plants as shown in U.S. Pat. No. 3,893,269. It is also known that triacontanol, which is a straight chained thirty carbon saturated alcohol having the formula CH.sub.3 (CH.sub.2).sub.28 CH.sub.2 OH, has plant growth characteristics. See, for example, Ries, et al., Science Mar. 25, 1977, Vol. 195 pp. 1339-1341. It has long been known that there are various plant growth hormones consisting of auxins, cytokinins, brassins and gibberellins. Cytokinins are obtained as extracts from seaweed and zeatin. Cytokinins may be regarded as derivatives of adenine, a purine compound. The biological effects of cytokinins are stated to be cell division, preservation of chlorophyll, expansion of young leaves, formation of new shoots or roots, outgrowth of lateral buds, promotion of seed germination and breaking of dormancy.
Auxins which include indoleacetic acid and derivatives thereof and gibberellins which include gibberellic acid and its derivatives increase fruit set and stimulate the sprouting of buds. These hormones are usually obtained from seaweed extracts and rice respectively.
The brassins are obtained from rape pollen and are a group of unidentified compounds that induce elongation of plants. It is thought that these compounds have a glyceride structure.
The presently known essential polyvalent metals in plant nutrition and biological development are calcium, magnesium, zinc, iron, manganese, copper, cobalt, molybdenum and boron. There is also evidence that other elements, such as selenium may have significant, direct or indirect, influence on biological activity.
Metals are believed to be mobilized in biological tissues through the formation of metal chelates, and if the metabolism of the organism does not readily facilitate chelate formation, metal assimilation and transport will be inhibited. Metal chelates which are also referred to as metal proteinates as will be hereinafter described are superior to inorganic metal compounds in facilitating metal absorption and transport because many plants have an inherent defect which inhibits natural endogenic synthesis of metal chelates.
The term "chelate" is stated in Webster's Seventh New Collegiate Dictionary, 1965, as being derived from the Greek chele meaning "claw" and is defined as "of relating to, or having a cyclic structure usually containing five or six atoms in a ring in which a central metallic ion is held in a coordination complex." A chelate has no net electrical charge on the central metal ion.
In connection with the above definition, metal chelates are herein defined to mean an essential metal atom attached by more than one donor atom of a ligand in such a manner as to form a heterocyclic ring by coordination complex bonding. By coordinate complex bonding is meant both covalent and ionic bonding. The term ligand refers to atoms, ions or molecules of hydrolyzed protein which are capable of functioning as the donor partner in one or more coordinate bonds. In other words, the ligand is electron rich and/or proton deficient. Ligands having two or more atoms which can simultaneously serve as donors are sometimes called polydentate ligands. Polydentate ligands whose structures permit the attachment of two or more donor sites to the same metal ion simultaneously, thus closing one or more heterocyclic rings, are called chelate ligands. In this specification, the terms chelate ligand and ligand will be used interchangeably and will preferably be referred to as ligand.
From the above it is apparent that a ligand must have available electrons in order to react with the metal ion to form a coordination complex or chelate. Obviously, the more acidic a solution is the more protons will interfere or compete for electrons and the less readily a chelate will form. Therefore, in the case of protein hydrolysates, i.e. polypeptides, peptides and naturally occurring amino acids the alpha amino groups (--NH.sub.2) should be free from interfering protons (NH.sub.3.sup..sym.) and the carboxylic acid groups should have the protons removed to from carboxy (--COO.sup..crclbar.) groups. This is a situation which occurs when the pH is more basic than the isoelectric point of the particular molecule in question. While each molecule has its own isoelectric point or zwitter ionic state it is not possible to have a stated isoelectric point for a group of different molecules such as protein hydrolysates, and thus the terms must be described more functionally, i.e., the mixture must be sufficiently basic that interfering protons are removed from the protein hydrolysate ligand.
1-triacontanol (1-hydroxytriacontane) is a naturally occurring straight chain 30 carbon saturated aliphatic alcohol present in beeswax and the leaves of many plants, particularly alfalfa. Triacontanol is unique in its activity as compared to homologs thereof. Saturated fatty alcohols with chain lengths of 9, 10 and 11 carbon atoms are active inhibitors of apillary and terminal bud growth. Alcohols with 17 to 22 carbons and their esters show some growth activity. However, octocosanol, the 28 carbon homolog of triacontanol, applied in nutrient culture at the same concentration as triacontanol does not increase plant growth or water uptake.
Triacontanol, applied in nutrient culture solution to rice seedlings in minute quantities, caused an increase in dry weight and leaf areas of plants, such as corn, wheat, rice, soybeans, tomatoes, carrots, cucumbers, lettuce and other food plants.